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Liu Y, Jang H, Nussinov R. SHP2-EGFR States in Dephosphorylation Can Inform Selective SHP2 Inhibitors, Dampening RasGAP Action. J Phys Chem B 2024; 128:5175-5187. [PMID: 38747619 DOI: 10.1021/acs.jpcb.4c00873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
SHP2 is a positive regulator of the EGFR-dependent Ras/MAPK pathway. It dephosphorylates a regulatory phosphorylation site in EGFR that serves as the binding site to RasGAP (RASA1 or p120RasGAP). RASA1 is activated by binding to the EGFR phosphate group. Active RASA1 deactivates Ras by hydrolyzing Ras-bound GTP to GDP. Thus, SHP2 dephosphorylation of EGFR effectively prevents RASA1-mediated deactivation of Ras, thereby stimulating proliferation. Despite knowledge of this vital regulation in cell life, mechanistic in-depth structural understanding of the involvement of SHP2, EGFR, and RASA1 in the Ras/MAPK pathway has largely remained elusive. Here we elucidate the interactions, the factors influencing EGFR's recruitment of RASA1, and SHP2's recognition of the substrate site in EGFR. We reveal that RASA1 specifically interacts with the DEpY992LIP motif in EGFR featuring a proline residue at the +3 position C-terminal to pY primarily through its nSH2 domain. This interaction is strengthened by the robust attraction of two acidic residues, E991 and D990, of EGFR to two basic residues in the BC-loop near the pY-binding pocket of RASA1's nSH2. In the stable precatalytic state of SHP2 with EGFR (DADEpY992LIPQ), the E-loop of SHP2's active site favors the interaction with the (-2)-position D990 and (-4)-position D988 N-terminal to pY992 in EGFR, while the pY-loop constrains the (+4)-position Q996 C-terminal to pY992. These specific interactions not only provide a structural basis for identifying negative regulatory sites in other RTKs but can inform selective, high-affinity active-site SHP2 inhibitors tailored for SHP2 mutants.
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Affiliation(s)
- Yonglan Liu
- Cancer Innovation Laboratory, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Hyunbum Jang
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Ruth Nussinov
- Computational Structural Biology Section, Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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2
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Wang J, Wang C, Hu A, Yu K, Kuang Y, Gajendran B, Zacksenhaus E, Sample KM, Xiao X, Liu W, Ben-David Y. FLI1 induces erythroleukemia through opposing effects on UBASH3A and UBASH3B expression. BMC Cancer 2024; 24:326. [PMID: 38461240 PMCID: PMC10925000 DOI: 10.1186/s12885-024-12075-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 03/01/2024] [Indexed: 03/11/2024] Open
Abstract
BACKGROUND FLI1 is an oncogenic transcription factor that promotes diverse malignancies through mechanisms that are not fully understood. Herein, FLI1 is shown to regulate the expression of Ubiquitin Associated and SH3 Domain Containing A/B (UBASH3A/B) genes. UBASH3B and UBASH3A are found to act as an oncogene and tumor suppressor, respectively, and their combined effect determines erythroleukemia progression downstream of FLI1. METHODS Promoter analysis combined with luciferase assays and chromatin immunoprecipitation (ChIP) analysis were applied on the UBASH3A/B promoters. RNAseq analysis combined with bioinformatic was used to determine the effect of knocking-down UBASH3A and UBASH3B in leukemic cells. Downstream targets of UBASH3A/B were inhibited in leukemic cells either via lentivirus-shRNAs or small molecule inhibitors. Western blotting and RT-qPCR were used to determine transcription levels, MTT assays to assess proliferation rate, and flow cytometry to examine apoptotic index. RESULTS Knockdown of FLI1 in erythroleukemic cells identified the UBASH3A/B genes as potential downstream targets. Herein, we show that FLI1 directly binds to the UBASH3B promoter, leading to its activation and leukemic cell proliferation. In contrast, FLI1 indirectly inhibits UBASH3A transcription via GATA2, thereby antagonizing leukemic growth. These results suggest oncogenic and tumor suppressor roles for UBASH3B and UBASH3A in erythroleukemia, respectively. Mechanistically, we show that UBASH3B indirectly inhibits AP1 (FOS and JUN) expression, and that its loss leads to inhibition of apoptosis and acceleration of proliferation. UBASH3B also positively regulates the SYK gene expression and its inhibition suppresses leukemia progression. High expression of UBASH3B in diverse tumors was associated with worse prognosis. In contrast, UBASH3A knockdown in erythroleukemic cells increased proliferation; and this was associated with a dramatic induction of the HSP70 gene, HSPA1B. Accordingly, knockdown of HSPA1B in erythroleukemia cells significantly accelerated leukemic cell proliferation. Accordingly, overexpression of UBASH3A in different cancers was predominantly associated with good prognosis. These results suggest for the first time that UBASH3A plays a tumor suppressor role in part through activation of HSPA1B. CONCLUSIONS FLI1 promotes erythroleukemia progression in part by modulating expression of the oncogenic UBASH3B and tumor suppressor UBASH3A.
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MESH Headings
- Humans
- Leukemia, Erythroblastic, Acute/genetics
- Leukemia, Erythroblastic, Acute/pathology
- Proto-Oncogene Protein c-fli-1/genetics
- Proto-Oncogene Protein c-fli-1/metabolism
- RNA, Small Interfering/genetics
- Genes, Tumor Suppressor
- Gene Expression Regulation
- Gene Expression Regulation, Neoplastic
- Cell Line, Tumor
- Oncogene Proteins, Fusion/genetics
- RNA-Binding Protein EWS/genetics
- Adaptor Proteins, Signal Transducing/metabolism
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Affiliation(s)
- Jie Wang
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China
| | - Chunlin Wang
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China
| | - Anling Hu
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China
| | - Kunlin Yu
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China
| | - Yi Kuang
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China
| | - Babu Gajendran
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- School of Pharmaceutical Sciences, Guizhou Medical University, Guizhou Province, Guiyang, 550025, People's Republic of China
| | - Eldad Zacksenhaus
- Department of Medicine, University of Toronto, Toronto, ON, Canada
- Division of Advanced Diagnostics, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | | | - Xiao Xiao
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China
| | - Wuling Liu
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China.
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China.
| | - Yaacov Ben-David
- State Key Laboratory for Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang-550014, Guizhou, People's Republic of China.
- Natural Products Research Center of Guizhou Province, High Tech Zone, Province Science City, Baiyun District, Guiyang, 550014, China.
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3
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Singh PK, Dangelmaier CA, Vari HR, Tsygankov AY, Kunapuli SP. Biochemical characterization of spleen tyrosine kinase (SYK) isoforms in platelets. Platelets 2023; 34:2249549. [PMID: 37661351 PMCID: PMC10502920 DOI: 10.1080/09537104.2023.2249549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/12/2023] [Accepted: 08/14/2023] [Indexed: 09/05/2023]
Abstract
Alternate splicing is among the regulatory mechanisms imparting functional diversity in proteins. Studying protein isoforms generated through alternative splicing is therefore critical for understanding protein functions in many biological systems. Spleen tyrosine kinase (Syk) plays an essential role in ITAM/hemITAM signaling in many cell types, including platelets. However, the spectrum of Syk isoforms expressed in platelets has not been characterized. Syk has been shown to have a full-length long isoform SykL and a shorter SykS lacking 23 amino acid residues within its interdomain B. Furthermore, putative isoforms lacking another 23 amino acid-long sequence or a combination of the two deletions have been postulated to exist. In this report, we demonstrate that mouse platelets express full-length SykL and the previously described shorter isoform SykS, but lack other shorter isoforms, whereas human platelets express predominantly SykL. These results both indicate a possible role of alternative Syk splicing in the regulation of receptor signaling in mouse platelets and a difference between signaling regulation in mouse and human platelets.
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Affiliation(s)
- Pankaj Kumar Singh
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Carol A. Dangelmaier
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Hymavathi Reddy Vari
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Alexander Y. Tsygankov
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Satya P. Kunapuli
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
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4
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Dangelmaier CA, Patchin M, Vajipayajula DN, Vari HR, Singh PK, Wright MN, Kostyak JC, Tsygankov AY, Kunapuli SP. Phosphorylation of spleen tyrosine kinase at Y346 negatively regulates ITAM-mediated signaling and function in platelets. J Biol Chem 2023; 299:104865. [PMID: 37268160 PMCID: PMC10320515 DOI: 10.1016/j.jbc.2023.104865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 04/29/2023] [Accepted: 05/02/2023] [Indexed: 06/04/2023] Open
Abstract
Spleen tyrosine kinase (Syk) is expressed in a variety of hemopoietic cells. Upon phosphorylation of the platelet immunoreceptor-based activation motif of the glycoprotein VI (GPVI)/Fc receptor gamma chain collagen receptor, both the tyrosine phosphorylation and activity of Syk are increased leading to downstream signaling events. Although it has been established that the activity of Syk is regulated by tyrosine phosphorylation, the specific roles of individual phosphorylation sites remain to be elucidated. We observed that Syk Y346 in mouse platelets was still phosphorylated when GPVI-induced Syk activity was inhibited. We then generated Syk Y346F mice and analyzed the effect this mutation exerts on platelet responses. Syk Y346F mice bred normally, and their blood cell count was unaltered. We did observe potentiation of GPVI-induced platelet aggregation and ATP secretion as well as increased phosphorylation of other tyrosines on Syk in the Syk Y346F mouse platelets when compared to WT littermates. This phenotype was specific for GPVI-dependent activation, since it was not seen when AYPGKF, a PAR4 agonist, or 2-MeSADP, a purinergic receptor agonist, was used to activate platelets. Despite a clear effect of Syk Y346F on GPVI-mediated signaling and cellular responses, there was no effect of this mutation on hemostasis as measured by tail-bleeding times, although the time to thrombus formation determined using the ferric chloride injury model was reduced. Thus, our results indicate a significant effect of Syk Y346F on platelet activation and responses in vitro and reveal its complex nature manifesting itself by the diversified translation of platelet activation into physiological responses.
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Affiliation(s)
- Carol A Dangelmaier
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Margaret Patchin
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Dhruv N Vajipayajula
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Hymavathi Reddy Vari
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Pankaj K Singh
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Monica N Wright
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - John C Kostyak
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Alexander Y Tsygankov
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Satya P Kunapuli
- Department of Cardiovascular Sciences, Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA.
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5
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Hayes B, van der Geer P. STS-1 and STS-2, Multi-Enzyme Proteins Equipped to Mediate Protein-Protein Interactions. Int J Mol Sci 2023; 24:ijms24119214. [PMID: 37298164 DOI: 10.3390/ijms24119214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 05/10/2023] [Accepted: 05/12/2023] [Indexed: 06/12/2023] Open
Abstract
STS-1 and STS-2 form a small family of proteins that are involved in the regulation of signal transduction by protein-tyrosine kinases. Both proteins are composed of a UBA domain, an esterase domain, an SH3 domain, and a PGM domain. They use their UBA and SH3 domains to modify or rearrange protein-protein interactions and their PGM domain to catalyze protein-tyrosine dephosphorylation. In this manuscript, we discuss the various proteins that have been found to interact with STS-1 or STS-2 and describe the experiments used to uncover their interactions.
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Affiliation(s)
- Barbara Hayes
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Dr., San Diego, CA 92105, USA
| | - Peter van der Geer
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Dr., San Diego, CA 92105, USA
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6
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Tsygankov AY. TULA Proteins in Men, Mice, Hens, and Lice: Welcome to the Family. Int J Mol Sci 2023; 24:ijms24119126. [PMID: 37298079 DOI: 10.3390/ijms24119126] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/16/2023] [Accepted: 05/18/2023] [Indexed: 06/12/2023] Open
Abstract
The two members of the UBASH3/STS/TULA protein family have been shown to critically regulate key biological functions, including immunity and hemostasis, in mammalian biological systems. Negative regulation of signaling through immune receptor tyrosine-based activation motif (ITAM)- and hemITAM-bearing receptors mediated by Syk-family protein tyrosine kinases appears to be a major molecular mechanism of the down-regulatory effect of TULA-family proteins, which possess protein tyrosine phosphatase (PTP) activity. However, these proteins are likely to carry out some PTP-independent functions as well. Whereas the effects of TULA-family proteins overlap, their characteristics and their individual contributions to cellular regulation also demonstrate clearly distinct features. Protein structure, enzymatic activity, molecular mechanisms of regulation, and biological functions of TULA-family proteins are discussed in this review. In particular, the usefulness of the comparative analysis of TULA proteins in various metazoan taxa, for identifying potential roles of TULA-family proteins outside of their functions already established in mammalian systems, is examined.
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Affiliation(s)
- Alexander Y Tsygankov
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
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7
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Zaman A, French JB, Carpino N. The Sts Proteins: Modulators of Host Immunity. Int J Mol Sci 2023; 24:8834. [PMID: 37240179 PMCID: PMC10218301 DOI: 10.3390/ijms24108834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/08/2023] [Accepted: 05/10/2023] [Indexed: 05/28/2023] Open
Abstract
The suppressor of TCR signaling (Sts) proteins, Sts-1 and Sts-2, are a pair of closely related signaling molecules that belong to the histidine phosphatase (HP) family of enzymes by virtue of an evolutionarily conserved C-terminal phosphatase domain. HPs derive their name from a conserved histidine that is important for catalytic activity and the current evidence indicates that the Sts HP domain plays a critical functional role. Sts-1HP has been shown to possess a readily measurable protein tyrosine phosphatase activity that regulates a number of important tyrosine-kinase-mediated signaling pathways. The in vitro catalytic activity of Sts-2HP is significantly lower than that of Sts-1HP, and its signaling role is less characterized. The highly conserved unique structure of the Sts proteins, in which additional domains, including one that exhibits a novel phosphodiesterase activity, are juxtaposed together with the phosphatase domain, suggesting that Sts-1 and -2 occupy a specialized intracellular signaling niche. To date, the analysis of Sts function has centered predominately around the role of Sts-1 and -2 in regulating host immunity and other responses associated with cells of hematopoietic origin. This includes their negative regulatory role in T cells, platelets, mast cells and other cell types, as well as their less defined roles in regulating host responses to microbial infection. Regarding the latter, the use of a mouse model lacking Sts expression has been used to demonstrate that Sts contributes non-redundantly to the regulation of host immunity toward a fungal pathogen (C. albicans) and a Gram-negative bacterial pathogen (F. tularensis). In particular, Sts-/- animals demonstrate significant resistance to lethal infections of both pathogens, a phenotype that is correlated with some heightened anti-microbial responses of phagocytes derived from mutant mice. Altogether, the past several years have seen steady progress in our understanding of Sts biology.
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Affiliation(s)
- Anika Zaman
- Graduate Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Jarrod B. French
- Hormel Institute, University of Minnesota, 801 16th Ave NE, Austin, MN 55912, USA;
| | - Nick Carpino
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794, USA
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8
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Zhang P, Solari FA, Heemskerk JWM, Kuijpers MJE, Sickmann A, Walter U, Jurk K. Differential Regulation of GPVI-Induced Btk and Syk Activation by PKC, PKA and PP2A in Human Platelets. Int J Mol Sci 2023; 24:ijms24097776. [PMID: 37175486 PMCID: PMC10178361 DOI: 10.3390/ijms24097776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/17/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023] Open
Abstract
Bruton's tyrosine kinase (Btk) and spleen tyrosine kinase (Syk) are major signaling proteins in human platelets that are implicated in atherothrombosis and thrombo-inflammation, but the mechanisms controlling their activities are not well understood. Previously, we showed that Syk becomes phosphorylated at S297 in glycoprotein VI (GPVI)-stimulated human platelets, which limits Syk activation. Here, we tested the hypothesis that protein kinases C (PKC) and A (PKA) and protein phosphatase 2A (PP2A) jointly regulate GPVI-induced Btk activation in platelets. The GPVI agonist convulxin caused rapid, transient Btk phosphorylation at S180 (pS180↑), Y223 and Y551, while direct PKC activation strongly increased Btk pS180 and pY551. This increase in Btk pY551 was also Src family kinase (SFK)-dependent, but surprisingly Syk-independent, pointing to an alternative mechanism of Btk phosphorylation and activation. PKC inhibition abolished convulxin-stimulated Btk pS180 and Syk pS297, but markedly increased the tyrosine phosphorylation of Syk, Btk and effector phospholipase Cγ2 (PLCγ2). PKA activation increased convulxin-induced Btk activation at Y551 but strongly suppressed Btk pS180 and Syk pS297. PP2A inhibition by okadaic acid only increased Syk pS297. Both platelet aggregation and PLCγ2 phosphorylation with convulxin stimulation were Btk-dependent, as shown by the selective Btk inhibitor acalabrutinib. Together, these results revealed in GPVI-stimulated platelets a transient Syk, Btk and PLCγ2 phosphorylation at multiple sites, which are differentially regulated by PKC, PKA or PP2A. Our work thereby demonstrated the GPVI-Syk-Btk signalosome as a tightly controlled protein kinase network, in agreement with its role in atherothrombosis.
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Affiliation(s)
- Pengyu Zhang
- Leibniz Institut für Analytische Wissenschaften-ISAS-e.V., 44139 Dortmund, Germany
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz, Germany
- Department of Biochemistry, CARIM, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Fiorella A Solari
- Leibniz Institut für Analytische Wissenschaften-ISAS-e.V., 44139 Dortmund, Germany
| | - Johan W M Heemskerk
- Department of Biochemistry, CARIM, Maastricht University, 6229 ER Maastricht, The Netherlands
- Synapse Research Institute Maastricht, 6217 KD Maastricht, The Netherlands
| | - Marijke J E Kuijpers
- Department of Biochemistry, CARIM, Maastricht University, 6229 ER Maastricht, The Netherlands
| | - Albert Sickmann
- Leibniz Institut für Analytische Wissenschaften-ISAS-e.V., 44139 Dortmund, Germany
- Medizinische Fakultät, Medizinisches Proteom-Center, Ruhr-Universität Bochum, 44780 Bochum, Germany
- Department of Chemistry, College of Physical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Ulrich Walter
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz, Germany
| | - Kerstin Jurk
- Center for Thrombosis and Hemostasis (CTH), University Medical Center of the Johannes Gutenberg University Mainz, 55131 Mainz, Germany
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9
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Kunapuli SP, Tsygankov AY. TULA-Family Regulators of Platelet Activation. Int J Mol Sci 2022; 23:ijms232314910. [PMID: 36499237 PMCID: PMC9736690 DOI: 10.3390/ijms232314910] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/17/2022] [Accepted: 11/21/2022] [Indexed: 11/30/2022] Open
Abstract
The two members of the UBASH3/TULA/STS-protein family have been shown to critically regulate cellular processes in multiple biological systems. The regulatory function of TULA-2 (also known as UBASH3B or STS-1) in platelets is one of the best examples of the involvement of UBASH3/TULA/STS proteins in cellular regulation. TULA-2 negatively regulates platelet signaling mediated by ITAM- and hemITAM-containing membrane receptors that are dependent on the protein tyrosine kinase Syk, which currently represents the best-known dephosphorylation target of TULA-2. The biological responses of platelets to collagen and other physiological agonists are significantly downregulated as a result. The protein structure, enzymatic activity and regulatory functions of UBASH3/TULA/STS proteins in the context of platelet responses and their regulation are discussed in this review.
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10
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Kostyak JC, Mauri B, Dangelmaier C, Vari HR, Patel A, Wright M, Reddy H, Tsygankov AY, Kunapuli SP. Phosphorylation on Syk Y342 is important for both ITAM and hemITAM signaling in platelets. J Biol Chem 2022; 298:102189. [PMID: 35753354 PMCID: PMC9287148 DOI: 10.1016/j.jbc.2022.102189] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 11/29/2022] Open
Abstract
Immune cells express receptors bearing an immune tyrosine activation motif (ITAM) containing two YXXL motifs or hemITAMs containing only one YXXL motif. Phosphorylation of the ITAM/hemITAM is mediated by Src family kinases allowing for the binding and activation of spleen tyrosine kinase (Syk). It is believed that Syk must be phosphorylated on tyrosine residues for activation, and Tyr342, а conserved tyrosine in the interdomain B region, has been shown to be critical for regulating Syk in FcεR1-activated mast cells. Syk is a key mediator of signaling pathways downstream of several platelet pathways including the ITAM bearing glycoprotein VI (GPVI)/Fc receptor gamma chain collagen receptor and the hemITAM containing C-type lectin-like receptor-2 (CLEC-2). Since platelet activation is a crucial step in both hemostasis and thrombosis, we evaluated the importance of Syk Y342 in these processes by producing an Syk Y342F knock-in mouse. When using a CLEC-2 antibody as an agonist, reduced aggregation and secretion were observed in Syk Y342F mouse platelets when compared with control mouse platelets. Platelet reactivity was also reduced in response to the GPVI agonist collagen-related peptide. Signaling initiated by either GPVI or CLEC-2 was also greatly inhibited, including Syk Y519/520 phosphorylation. Hemostasis, as measured by tail bleeding time, was not altered in Syk Y342F mice, but thrombus formation in response to FeCl3 injury was prolonged in Syk Y342F mice. These data demonstrate that phosphorylation of Y342 on Syk following stimulation of either GPVI or CLEC-2 receptors is important for the ability of Syk to transduce a signal.
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Affiliation(s)
- John C Kostyak
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Benjamin Mauri
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Carol Dangelmaier
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Hymavathi Reddy Vari
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Akruti Patel
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Monica Wright
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Haritha Reddy
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Alexander Y Tsygankov
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA
| | - Satya P Kunapuli
- Sol Sherry Thrombosis Research Center and Department of Cardiovascular Sciences, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, USA.
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11
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Ge Y, Paisie TK, Chen S, Concannon P. UBASH3A Regulates the Synthesis and Dynamics of TCR-CD3 Complexes. THE JOURNAL OF IMMUNOLOGY 2019; 203:2827-2836. [PMID: 31659016 DOI: 10.4049/jimmunol.1801338] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 09/27/2019] [Indexed: 01/14/2023]
Abstract
The TCR-CD3 complex is a multicomponent membrane receptor, the expression of which is tightly regulated in thymocytes, as well as in mature T cells both at steady state and upon stimulation. In this study, we report novel roles for UBASH3A in TCR-CD3 synthesis and turnover. UBASH3A is a negative regulator of T cell function and plays a broad role in autoimmunity. We show that modulation of UBASH3A levels in unstimulated Jurkat cells leads to altered amounts of total cellular CD3 chains and of cell-surface TCR-CD3 complexes; in contrast, UBASH3A does not affect the level of cell-surface CD28, an important T cell costimulatory receptor. Upon TCR engagement, UBASH3A enhances the downmodulation of cell-surface TCR-CD3. Mass spectrometry and protein-protein interaction studies uncover novel associations between UBASH3A and components of several cellular pathways involved in the regulation of TCR-CD3 turnover and dynamics, including endoplasmic reticulum-associated protein degradation, cell motility, endocytosis, and endocytic recycling of membrane receptors. Finally, we demonstrate that the SH3 domain of UBASH3A mediates its binding to CBL-B, an E3 ubiquitin ligase that negatively regulates CD28-mediated signaling and, hence, T cell activation. In summary, this study provides new mechanistic insights into how UBASH3A regulates T cell activation and contributes to autoimmunity. The interaction between UBASH3A and CBL-B may synergistically inhibit T cell function and affect risk for type 1 diabetes, as both genes have been shown to be associated with this autoimmune disease.
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Affiliation(s)
- Yan Ge
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL 32610; .,Genetics Institute, University of Florida, Gainesville, FL 32610
| | - Taylor K Paisie
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL 32610.,Genetics Institute, University of Florida, Gainesville, FL 32610.,Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL 32610
| | - Sixue Chen
- Genetics Institute, University of Florida, Gainesville, FL 32610.,Genetics and Genomics Graduate Program, University of Florida, Gainesville, FL 32610.,Department of Biology, University of Florida, Gainesville, FL 32611.,Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL 32611; and.,Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32610
| | - Patrick Concannon
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL 32610; .,Genetics Institute, University of Florida, Gainesville, FL 32610
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12
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Tsygankov AY. TULA proteins as signaling regulators. Cell Signal 2019; 65:109424. [PMID: 31639493 DOI: 10.1016/j.cellsig.2019.109424] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 10/25/2022]
Abstract
Two members of the UBASH3/STS/TULA family exhibit a unique protein domain structure, which includes a histidine phosphatase domain, and play a key role in regulating cellular signaling. UBASH3A/STS-2/TULA is mostly a lymphoid protein, while UBASH3B/STS-1/TULA-2 is expressed ubiquitously. Dephosphorylation of tyrosine-phosphorylated proteins by TULA-2 and, probably to a lesser extent, by TULA critically contribute to the molecular basis of their regulatory effect. The notable differences between the effects of the two family members on cellular signaling and activation are likely to be linked to the difference between their specific enzymatic activities. However, these differences might also be related to the functions of their domains other than the phosphatase domain and independent of their phosphatase activity. The down-regulation of the Syk/Zap-70-mediated signaling, which to-date appears to be the best-studied regulatory effect of TULA family, is discussed in detail in this publication.
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Affiliation(s)
- Alexander Y Tsygankov
- Sol Sherry Thrombosis Research Center, Fels Institute for Cancer Research and Department of Microbiology and Immunology, Lewis Katz School of Medicine at Temple University, 3400 N. Broad Street, Philadelphia, PA, 19140, United States.
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13
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Zhou W, Yin Y, Smith E, Chou J, Shumate J, Scampavia L, Spicer TP, Carpino N, French JB. Discovery and Characterization of Two Classes of Selective Inhibitors of the Suppressor of the TCR Signaling Family of Proteins. ACS Infect Dis 2019; 5:250-259. [PMID: 30485744 DOI: 10.1021/acsinfecdis.8b00238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The suppressor of T-cell receptor signaling (Sts) proteins, Sts-1, has recently emerged as a potential immunostimulatory target for drug development. Genetic inactivation of the Sts proteins dramatically increases host survival of systemic infection and leads to improved pathogen clearance. The protein tyrosine phosphatase (PTP) activity of these proteins arises from a C-terminal 2-histidine phosphatase (HP) domain. To identify new inhibitors of the HP activity of Sts-1, we miniaturized a phosphatase assay to a 1536-well format and conducted a 20 580 compound screen. Among the hits were two classes of structurally related compounds, tetracycline variants and sulfonated azo dyes. These hits had low micromolar to nanomolar IC50 values. Orthogonal screening confirmed the validity of these inhibitors and demonstrated that both act competitively on Sts-1 phosphatase activity. When tested on other PTPs, PTP1B and SHP1, it was found that the tetracycline PTP1B, SHP1, the tetracycline variant (doxycycline), and the sulfonated azo dye (Congo red) are selective inhibitors of Sts-1HP, with selectivity indices ranging from 19 to as high as 200. The planar polyaromatic moieties present in both classes of compounds suggested a common binding mode. The mutation of either tryptophan 494 or tyrosine 596, located near the active site of the protein, reduced the Ki of the inhibitors from 3- to 18-fold, indicating that these residues may help to promote the binding of substrates with aromatic groups. This work provides new insights into substrate selectivity mechanisms and describes two classes of compounds that can serve as probes of function or as a basis for future drug discovery.
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Affiliation(s)
| | | | - Emery Smith
- Department of Molecular Medicine, Scripps Research Molecular Screening Center, Scripps Research, 130 Scripps Way, Jupiter, Florida 33458, United States
| | | | - Justin Shumate
- Department of Molecular Medicine, Scripps Research Molecular Screening Center, Scripps Research, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Louis Scampavia
- Department of Molecular Medicine, Scripps Research Molecular Screening Center, Scripps Research, 130 Scripps Way, Jupiter, Florida 33458, United States
| | - Timothy P. Spicer
- Department of Molecular Medicine, Scripps Research Molecular Screening Center, Scripps Research, 130 Scripps Way, Jupiter, Florida 33458, United States
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14
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Kostyak JC, Mauri BR, Dangelmaier C, Patel A, Zhou Y, Eble JA, Tsygankov AY, McKenzie SE, Kunapuli SP. TULA-2 Deficiency Enhances Platelet Functional Responses to CLEC-2 Agonists. TH OPEN 2018; 2:e411-e419. [PMID: 31249969 PMCID: PMC6524918 DOI: 10.1055/s-0038-1676358] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 10/10/2018] [Indexed: 02/06/2023] Open
Abstract
Platelet activation is essential for hemostasis. Central to platelet activation are the signals transmitted through surface receptors such as glycoprotein VI, the protease-activated receptors, and C-type lectin-like receptor 2 (CLEC-2). CLEC-2 is a HemITAM (hem-immunoreceptor tyrosine activation motif)-bearing receptor that binds podoplanin and signals through spleen tyrosine kinase (Syk). T-cell ubiquitin ligand-2 (TULA-2) is a protein tyrosine phosphatase that is highly expressed in platelets and targets phosphorylated Y352 of Syk. We wanted to determine whether TULA-2 regulates Syk phosphorylation and activity downstream of CLEC-2. To that end, we used TULA-2 knockout mice and wild-type (WT) littermate controls. We found that TULA-2 deficiency enhances the aggregation and secretion response following stimulation with an excitatory CLEC-2 antibody or the CLEC-2 agonist rhodocytin. Consistently, Syk phosphorylation of Y346 is enhanced, as well as phosphorylation of the downstream signaling molecule PLCγ2, in TULA-2 knockout platelets treated with either CLEC-2 antibody or rhodocytin, compared with WT control platelets. Furthermore, the kinetics of Syk phosphorylation, as well as that of PLCγ2 and SLP-76, is enhanced in TULA-2 knockout platelets treated with 2.5-μg/mL CLEC-2 antibody compared with WT platelets. Similarly, thromboxane production was enhanced, in both amount and kinetics, in TULA-2
−/−
platelets treated with 2.5-μg/mL CLEC-2 antibody. TULA-2 acts as a negative regulator of CLEC-2 signaling by dephosphorylating Syk on Y346 and restraining subsequent Syk-mediated signaling.
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Affiliation(s)
- John C Kostyak
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Benjamin R Mauri
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Carol Dangelmaier
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Akruti Patel
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Yuhang Zhou
- Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - Johannes A Eble
- Institute of Physiological Chemistry and Pathobiochemistry, University of Munster, Waldeyerstasse, Munster, Germany
| | - Alexander Y Tsygankov
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States.,Department of Immunology and Microbiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
| | - Steven E McKenzie
- Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
| | - Satya P Kunapuli
- Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
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15
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Barrett R, Jiang S, White AD. Classifying antimicrobial and multifunctional peptides with Bayesian network models. Pept Sci (Hoboken) 2018. [DOI: 10.1002/pep2.24079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Rainier Barrett
- Department of Chemical Engineering University of Rochester Rochester New York
| | - Shaoyi Jiang
- Department of Chemical Engineering University of Washington Seattle Washington
| | - Andrew D. White
- Department of Chemical Engineering University of Rochester Rochester New York
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16
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Tsygankov AY. TULA-family proteins: Jacks of many trades and then some. J Cell Physiol 2018; 234:274-288. [PMID: 30076707 DOI: 10.1002/jcp.26890] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 06/13/2018] [Indexed: 12/17/2022]
Abstract
UBASH3/STS/TULA is a novel two-member family, which exerts several key regulatory effects in multiple cell types. UBASH3B/STS-1/TULA-2 is a highly active protein tyrosine phosphatase; its major target appears to be a specific regulatory site of protein tyrosine kinases of the Syk family, dephosphorylation of which inhibits Syk and Zap-70 kinases and suppresses receptor signaling mediated by these kinases. UBASH3A/STS-2/TULA exhibits substantial homology to UBASH3B/STS-1/TULA-2, but possesses only a small fraction of phosphatase activity of UBASH3B/STS-1/TULA-2, and thus, its regulatory effect may be based also on the phosphatase-independent mechanisms. Critical physiologic effects of these proteins have been demonstrated in T lymphocytes, platelets, stem cells, and other important cell types. These proteins have also been shown to play a key role in such pathologic conditions as autoimmunity, cancer, and thrombosis. The review focuses on the recent studies of this important family of cellular regulators.
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Affiliation(s)
- Alexander Y Tsygankov
- Department of Microbiology and Immunology, Fels Institute for Cancer Research and Molecular Biology and Sol Sherry Thrombosis Center, Temple University School of Medicine, Philadelphia, Pennsylvania
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17
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Abstract
In higher eukaryotes, the Tyr phosphorylation status of cellular proteins results from the coordinated action of Protein Tyrosine Kinases (PTKs) and Protein Tyrosine Phosphatases (PTPs). PTPs have emerged as highly regulated enzymes with diverse substrate specificity, and proteins with Tyr-dephosphorylation or Tyr-dephosphorylation-like properties can be clustered as the PTPome. This includes proteins from the PTP superfamily, which display a Cys-based catalytic mechanism, as well as enzymes from other gene families (Asp-based phosphatases, His-based phosphatases) that have converged in protein Tyr-dephosphorylation-related functions by using non-Cys-based catalytic mechanisms. Within the Cys-based members of the PTPome, classical PTPs dephosphorylate specific phosphoTyr (pTyr) residues from protein substrates, whereas VH1-like dual-specificity PTPs dephosphorylate pTyr, pSer, and pThr residues, as well as nonproteinaceous substrates, including phosphoinositides and phosphorylated carbohydrates. In addition, several PTPs have impaired catalytic activity as a result of amino acid substitutions at their active sites, but retain regulatory functions related with pTyr signaling. As a result of their relevant biological activity, many PTPs are linked to human disease, including cancer, neurodevelopmental, and metabolic diseases, making these proteins important drug targets and molecular markers in the clinic. Here, a brief overview on the biochemistry and physiology of the different groups of proteins that belong to the mammalian PTPome is presented.
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18
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Ge Y, Paisie TK, Newman JRB, McIntyre LM, Concannon P. UBASH3A Mediates Risk for Type 1 Diabetes Through Inhibition of T-Cell Receptor-Induced NF-κB Signaling. Diabetes 2017; 66:2033-2043. [PMID: 28607106 PMCID: PMC5482087 DOI: 10.2337/db16-1023] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 03/20/2017] [Indexed: 01/19/2023]
Abstract
Although over 40 type 1 diabetes (T1D) risk loci have been mapped in humans, the causative genes and variants for T1D are largely unknown. Here, we investigated a candidate gene in the 21q22.3 risk locus-UBASH3A, which is primarily expressed in T cells where it is thought to play a largely redundant role. Genetic variants in UBASH3A have been shown to be associated with several autoimmune diseases in addition to T1D. However, the molecular mechanism underlying these genetic associations is unresolved. Our study reveals a previously unrecognized role of UBASH3A in human T cells: UBASH3A attenuates the NF-κB signal transduction upon T-cell receptor (TCR) stimulation by specifically suppressing the activation of the IκB kinase complex. We identify novel interactions of UBASH3A with nondegradative polyubiquitin chains, TAK1 and NEMO, suggesting that UBASH3A regulates the NF-κB signaling pathway by an ubiquitin-dependent mechanism. Finally, we show that risk alleles at rs11203203 and rs80054410, two T1D-associated variants in UBASH3A, increase UBASH3A expression in human primary CD4+ T cells upon TCR stimulation, inhibiting NF-κB signaling via its effects on the IκB kinase complex and resulting in reduced IL2 gene expression.
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Affiliation(s)
- Yan Ge
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL
- Genetics Institute, University of Florida, Gainesville, FL
| | - Taylor K Paisie
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL
- Genetics Institute, University of Florida, Gainesville, FL
- Genetics & Genomics Graduate Program, University of Florida, Gainesville, FL
| | - Jeremy R B Newman
- Genetics Institute, University of Florida, Gainesville, FL
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL
| | - Lauren M McIntyre
- Genetics Institute, University of Florida, Gainesville, FL
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL
| | - Patrick Concannon
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida, Gainesville, FL
- Genetics Institute, University of Florida, Gainesville, FL
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19
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Chen MJ, Dixon JE, Manning G. Genomics and evolution of protein phosphatases. Sci Signal 2017; 10:10/474/eaag1796. [DOI: 10.1126/scisignal.aag1796] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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20
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Cutler JA, Tahir R, Sreenivasamurthy SK, Mitchell C, Renuse S, Nirujogi RS, Patil AH, Heydarian M, Wong X, Wu X, Huang TC, Kim MS, Reddy KL, Pandey A. Differential signaling through p190 and p210 BCR-ABL fusion proteins revealed by interactome and phosphoproteome analysis. Leukemia 2017; 31:1513-1524. [DOI: 10.1038/leu.2017.61] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/04/2017] [Accepted: 01/11/2017] [Indexed: 12/15/2022]
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21
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Zhou Y, Abraham S, Renna S, Edelstein LC, Dangelmaier CA, Tsygankov AY, Kunapuli SP, Bray PF, McKenzie SE. TULA-2 (T-Cell Ubiquitin Ligand-2) Inhibits the Platelet Fc Receptor for IgG IIA (FcγRIIA) Signaling Pathway and Heparin-Induced Thrombocytopenia in Mice. Arterioscler Thromb Vasc Biol 2016; 36:2315-2323. [PMID: 27765766 DOI: 10.1161/atvbaha.116.307979] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 10/04/2016] [Indexed: 12/19/2022]
Abstract
OBJECTIVE The objective of this study is to investigate the role of T-cell ubiquitin ligand-2 (TULA-2) in the platelet Fc receptor for IgG IIA (FcγRIIA) pathway and in the pathogenesis of heparin-induced thrombocytopenia (HIT). APPROACH AND RESULTS HIT is a life-threatening thrombotic disease in which IgG antibodies against the heparin-platelet factor 4 complex activate platelets via FcγRIIA. We reported previously differential expression of TULA-2 in human population was linked to FcγRIIA responsiveness. In this study, we investigated the role of TULA-2, a protein phosphatase, in the FcγRIIA pathway and HIT pathogenesis by crossing TULA-2-/- mice with transgenic FcγRIIA +/+ mice. Ablation of TULA-2 resulted in hyperphosphorylation of spleen tyrosine kinase, linker for the activation of T cells, and phospholipase Cγ2 in platelets via FcγRIIA activation. Platelet integrin activation, granule secretion, phosphatidylserine exposure, and aggregation were also enhanced in TULA-2-/- murine platelets. Compared with wild-type mice, TULA-2-/- mice showed aggravated antibody-mediated thrombocytopenia, augmented thrombin generation, and shortened tail bleeding time. In contrast, there was no significant difference between TULA-2-/- and TULA-2+/+ platelets in platelet spreading and clot retraction. Of note, heterozygous TULA-2+/- mice, whose platelets contained 50% as much protein as the TULA-2+/+ platelets, showed significantly increased platelet reactivity and more severe thrombocytopenia in vivo compared with TULA-2+/+ mice. CONCLUSIONS Together, the data demonstrate that not only the absence of TULA-2 but also the relative level of TULA-2 expression modulates FcγRIIA-mediated platelet reactivity and HIT in vivo. TULA-2 expression could be a valuable marker for HIT and inhibiting TULA-2 may serve as a potential therapy to reverse the bleeding adverse effect of anticoagulants.
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Affiliation(s)
- Yuhang Zhou
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Shaji Abraham
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Stephanie Renna
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Leonard C Edelstein
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Carol A Dangelmaier
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Alexander Y Tsygankov
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Satya P Kunapuli
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Paul F Bray
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.)
| | - Steven E McKenzie
- From the Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA (Y.Z., S.A., S.R., L.C.E., P.F.B., S.E.M.); and Department of Physiology, Sol Sherry Thrombosis Research Center, Temple University, Philadelphia, PA (C.A.D., A.Y.T., S.P.K.).
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22
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Reppschläger K, Gosselin J, Dangelmaier CA, Thomas DH, Carpino N, McKenzie SE, Kunapuli SP, Tsygankov AY. TULA-2 Protein Phosphatase Suppresses Activation of Syk through the GPVI Platelet Receptor for Collagen by Dephosphorylating Tyr(P)346, a Regulatory Site of Syk. J Biol Chem 2016; 291:22427-22441. [PMID: 27609517 DOI: 10.1074/jbc.m116.743732] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 08/30/2016] [Indexed: 12/14/2022] Open
Abstract
Protein-tyrosine phosphatase TULA-2 has been shown to regulate receptor signaling in several cell types, including platelets. Platelets are critical for maintaining vascular integrity; this function is mediated by platelet aggregation in response to recognition of the exposed basement membrane collagen by the GPVI receptor, which is non-covalently associated with the signal-transducing FcRγ polypeptide chain. Our previous studies suggested that TULA-2 plays an important role in negatively regulating signaling through GPVI-FcRγ and indicated that the tyrosine-protein kinase Syk is a key target of the regulatory action of TULA-2 in platelets. However, the molecular basis of the down-regulatory effect of TULA-2 on Syk activation via FcRγ remained unclear. In this study, we demonstrate that suppression of Syk activation by TULA-2 is mediated, to a substantial degree, by dephosphorylation of Tyr(P)346, a regulatory site of Syk, which becomes phosphorylated soon after receptor ligation and plays a critical role in initiating the process that yields fully activated Syk. TULA-2 is capable of dephosphorylating Tyr(P)346 with high efficiency, thus controlling the overall activation of Syk, but is less efficient in dephosphorylating other regulatory sites of this kinase. Therefore, dephosphorylation of Tyr(P)346 may be considered an important "checkpoint" in the regulation of Syk activation process. Putative biological functions of TULA-2-mediated dephosphorylation of Tyr(P)346 may include deactivation of receptor-activated Syk or suppression of Syk activation by suboptimal stimulation.
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Affiliation(s)
- Kevin Reppschläger
- From the Departments of Microbiology and Immunology and.,Ernst-Moritz-Arndt-University Greifswald, 17489 Greifswald, Germany
| | - Jeanne Gosselin
- From the Departments of Microbiology and Immunology and.,Polytech Clermont-Ferrand, Ingenieur Genie Biologique, Clermont-Ferrand, Auvergne 63178, France, and
| | - Carol A Dangelmaier
- the Sol Sherry Thrombosis Research Center, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140
| | - Dafydd H Thomas
- the Sol Sherry Thrombosis Research Center, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140.,PMV Pharmaceuticals, Cranbury Township, New Jersey 08512
| | - Nick Carpino
- the Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, New York 11794
| | - Steven E McKenzie
- the Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Satya P Kunapuli
- the Sol Sherry Thrombosis Research Center, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140.,Physiology and
| | - Alexander Y Tsygankov
- From the Departments of Microbiology and Immunology and .,the Sol Sherry Thrombosis Research Center, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania 19140
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23
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Abstract
Protein kinases phosphorylate specific serine, threonine, and/or tyrosine residues in their target proteins, resulting in functional changes of the target proteins such as enzymatic activity, cellular location, or association with other proteins. For many kinases, their in vivo substrate specificity is at least partially defined by the amino acid sequence surrounding the phosphorylatable residue (or sequence specificity). We report here a robust, high-throughput method for profiling the sequence specificity of protein kinases. Up to 10(7) different peptides are rapidly synthesized on PEGA beads in the one-bead-one-compound format and subjected to kinase reaction in the presence of [γ-S]ATP. Positive beads displaying the optimal kinase substrates are identified by covalently labeling the thiophosphorylated peptides with a fluorescent dye via a disulfide exchange reaction. Finally, the most active hit(s) is identified by the partial Edman degradation-mass spectrometry (PED-MS) method. The ability of this method to provide individual sequences of the preferred substrates permits the identification of sequence contextual effects and non-permissive residues. This method is applicable to protein serine, threonine, and tyrosine kinases.
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24
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Regulation of Early Steps of GPVI Signal Transduction by Phosphatases: A Systems Biology Approach. PLoS Comput Biol 2015; 11:e1004589. [PMID: 26584182 PMCID: PMC4652868 DOI: 10.1371/journal.pcbi.1004589] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/06/2015] [Indexed: 11/19/2022] Open
Abstract
We present a data-driven mathematical model of a key initiating step in platelet activation, a central process in the prevention of bleeding following Injury. In vascular disease, this process is activated inappropriately and causes thrombosis, heart attacks and stroke. The collagen receptor GPVI is the primary trigger for platelet activation at sites of injury. Understanding the complex molecular mechanisms initiated by this receptor is important for development of more effective antithrombotic medicines. In this work we developed a series of nonlinear ordinary differential equation models that are direct representations of biological hypotheses surrounding the initial steps in GPVI-stimulated signal transduction. At each stage model simulations were compared to our own quantitative, high-temporal experimental data that guides further experimental design, data collection and model refinement. Much is known about the linear forward reactions within platelet signalling pathways but knowledge of the roles of putative reverse reactions are poorly understood. An initial model, that includes a simple constitutively active phosphatase, was unable to explain experimental data. Model revisions, incorporating a complex pathway of interactions (and specifically the phosphatase TULA-2), provided a good description of the experimental data both based on observations of phosphorylation in samples from one donor and in those of a wider population. Our model was used to investigate the levels of proteins involved in regulating the pathway and the effect of low GPVI levels that have been associated with disease. Results indicate a clear separation in healthy and GPVI deficient states in respect of the signalling cascade dynamics associated with Syk tyrosine phosphorylation and activation. Our approach reveals the central importance of this negative feedback pathway that results in the temporal regulation of a specific class of protein tyrosine phosphatases in controlling the rate, and therefore extent, of GPVI-stimulated platelet activation.
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Anti-miR-148a regulates platelet FcγRIIA signaling and decreases thrombosis in vivo in mice. Blood 2015; 126:2871-81. [PMID: 26516227 DOI: 10.1182/blood-2015-02-631135] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 10/21/2015] [Indexed: 12/27/2022] Open
Abstract
Fc receptor for IgG IIA (FcγRIIA)-mediated platelet activation is essential in heparin-induced thrombocytopenia (HIT) and other immune-mediated thrombocytopenia and thrombosis disorders. There is considerable interindividual variation in platelet FcγRIIA activation, the reasons for which remain unclear. We hypothesized that genetic variations between FcγRIIA hyper- and hyporesponders regulate FcγRIIA-mediated platelet reactivity and influence HIT susceptibility. Using unbiased genome-wide expression profiling, we observed that human hyporesponders to FcγRIIA activation showed higher platelet T-cell ubiquitin ligand-2 (TULA-2) mRNA expression than hyperresponders. Silent interfering RNA-mediated knockdown of TULA-2 resulted in hyperphosphorylation of spleen tyrosine kinase following FcγRIIA activation in HEL cells. Significantly, we found miR-148a-3p targeted and inhibited both human and mouse TULA-2 mRNA. Inhibition of miR-148a in FcγRIIA transgenic mice upregulated the TULA-2 level and reduced FcγRIIA- and glycoprotein VI-mediated platelet αIIbβ3 activation and calcium mobilization. Anti-miR-148a also reduced thrombus formation following intravascular platelet activation via FcγRIIA. These results show that TULA-2 is a target of miR-148a-3p, and TULA-2 serves as a negative regulator of FcγRIIA-mediated platelet activation. This is also the first study to show the effects of in vivo miRNA inhibition on platelet reactivity. Our work suggests that modulating miR-148a expression is a potential therapeutic approach for thrombosis.
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Members of the novel UBASH3/STS/TULA family of cellular regulators suppress T-cell-driven inflammatory responses in vivo. Immunol Cell Biol 2014; 92:837-50. [PMID: 25047644 DOI: 10.1038/icb.2014.60] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 06/17/2014] [Accepted: 06/17/2014] [Indexed: 01/03/2023]
Abstract
The UBASH3/STS/TULA family consists of two members sharing substantial homology and a similar multi-domain architecture, which includes a C-terminal histidine phosphatase domain capable of dephosphorylating phosphotyrosine-containing substrates. TULA-family proteins act as downregulators of receptor-induced activation in several cell types, including T cells and platelets. Deletion of both family members in mice has been shown to result in hyperresponsiveness of T cells to T-cell receptor (TCR)/CD3 complex engagement, but little is known about the biological consequences of double knockout (dKO) and especially of either single KO (sKO). We elucidated the biological consequences of the lack of TULA-family proteins in dKO and TULA and TULA-2 sKO animals. In order to do so, we examined immune responses in Trinitrobenzene sulfonic acid (TNBS)-induced colitis, a mouse model of human inflammatory bowel disease, which is characterized by the involvement of multiple cell types, of which T cells have a crucial role, in the development of a pathological inflammatory condition. Our data indicate that TNBS treatment upregulates T-cell responses in all KO mice studied to a significantly higher degree than in wild-type mice. Although the lack of either TULA-family member exacerbates inflammation and T-cell responses in a specific fashion, the lack of both TULA and TULA-2 in dKO exerts a higher effect than the lack of a single family member in TULA and TULA-2 sKO. Analysis of T-cell responses and TCR-mediated signaling argues that the proteins investigated affect T-cell signaling by regulating phosphorylation of Zap-70, a key protein tyrosine kinase.
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Luis BS, Carpino N. Insights into the suppressor of T-cell receptor (TCR) signaling-1 (Sts-1)-mediated regulation of TCR signaling through the use of novel substrate-trapping Sts-1 phosphatase variants. FEBS J 2014; 281:696-707. [PMID: 24256567 PMCID: PMC3968691 DOI: 10.1111/febs.12615] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 10/09/2013] [Accepted: 11/05/2013] [Indexed: 01/04/2023]
Abstract
High affinity substrate-trapping protein tyrosine phosphatases have been widely used both to investigate the endogenous targets of many phosphatases and to address questions of substrate specificity. Herein, we extend the concept of a substrate-trapping phosphatase to include an enzyme of the histidine phosphatase superfamily. This is the first description of substrate-trapping technology applied to a member of the histidine phosphatase family. The phosphatase suppressor of T-cell receptor signaling (Sts)-1 has recently been reported to negatively regulate signaling downstream of the T-cell receptor. We generated high-affinity substrate-trapping variants of Sts-1 by mutagenesis of key active site residues within the phosphatase catalytic domain. Mutation of both the nucleophilic His380 and the general acid Glu490 yielded Sts-1 enzymes that were catalytically inactive but showed high affinity for an important tyrosine kinase in T cells that Sts-1 is known to regulate, Zap-70. Sts-1 substrate-trapping mutants isolated tyrosine-phosphorylated Zap-70 from lysates of activated T cells, validating Zap-70 as a possible substrate for Sts-1 and highlighting the efficacy of the mutants as substrate-trapping agents. Inhibition of the Zap-70 interaction by vanadate suggests that the substrate-trapping effect occurred via the Sts-1 phosphatase active site. Finally, overexpression of Sts-1 substrate-trapping mutants in T cells blocked T-cell receptor signaling, confirming the inhibitory effect of Sts-1 on Zap-70.
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Affiliation(s)
- Boris S Luis
- Program in Molecular and Cellular Biology, Stony Brook University, NY, USA
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Selner NG, Luechapanichkul R, Chen X, Neel BG, Zhang ZY, Knapp S, Bell CE, Pei D. Diverse levels of sequence selectivity and catalytic efficiency of protein-tyrosine phosphatases. Biochemistry 2014; 53:397-412. [PMID: 24359314 PMCID: PMC3954597 DOI: 10.1021/bi401223r] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The sequence selectivity of 14 classical protein-tyrosine phosphatases (PTPs) (PTPRA, PTPRB, PTPRC, PTPRD, PTPRO, PTP1B, SHP-1, SHP-2, HePTP, PTP-PEST, TCPTP, PTPH1, PTPD1, and PTPD2) was systematically profiled by screening their catalytic domains against combinatorial peptide libraries. All of the PTPs exhibit similar preference for pY peptides rich in acidic amino acids and disfavor positively charged sequences but differ vastly in their degrees of preference/disfavor. Some PTPs (PTP-PEST, SHP-1, and SHP-2) are highly selective for acidic over basic (or neutral) peptides (by >10(5)-fold), whereas others (PTPRA and PTPRD) show no to little sequence selectivity. PTPs also have diverse intrinsic catalytic efficiencies (kcat/KM values against optimal substrates), which differ by >10(5)-fold due to different kcat and/or KM values. Moreover, PTPs show little positional preference for the acidic residues relative to the pY residue. Mutation of Arg47 of PTP1B, which is located near the pY-1 and pY-2 residues of a bound substrate, decreased the enzymatic activity by 3-18-fold toward all pY substrates containing acidic residues anywhere within the pY-6 to pY+5 region. Similarly, mutation of Arg24, which is situated near the C-terminus of a bound substrate, adversely affected the kinetic activity of all acidic substrates. A cocrystal structure of PTP1B bound with a nephrin pY(1193) peptide suggests that Arg24 engages in electrostatic interactions with acidic residues at the pY+1, pY+2, and likely other positions. These results suggest that long-range electrostatic interactions between positively charged residues near the PTP active site and acidic residues on pY substrates allow a PTP to bind acidic substrates with similar affinities, and the varying levels of preference for acidic sequences by different PTPs are likely caused by the different electrostatic potentials near their active sites. The implications of the varying sequence selectivity and intrinsic catalytic activities with respect to PTP in vivo substrate specificity and biological functions are discussed.
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Affiliation(s)
- Nicholas G. Selner
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12 Avenue, Columbus, OH 43210, USA
| | - Rinrada Luechapanichkul
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12 Avenue, Columbus, OH 43210, USA
| | - Xianwen Chen
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12 Avenue, Columbus, OH 43210, USA
| | - Benjamin G. Neel
- Princess Margaret Cancer Center, University Health Network, and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Room 7-504, Toronto, ON M5G 2M9, Canada
| | - Zhong-Yin Zhang
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Stefan Knapp
- Structural Genomics Consortium and Target Discovery Institute, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Charles E. Bell
- Department of Molecular and Cellular Biochemistry, The Ohio State University, 1645 Neil Avenue, Columbus, OH 43210
| | - Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12 Avenue, Columbus, OH 43210, USA
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New insights into the catalytic mechanism of histidine phosphatases revealed by a functionally essential arginine residue within the active site of the Sts phosphatases. Biochem J 2013; 453:27-35. [PMID: 23565972 DOI: 10.1042/bj20121769] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sts (suppressor of T-cell receptor signalling)-1 and Sts-2 are HPs (histidine phosphatases) that negatively regulate TCR (T-cell receptor) signalling pathways, including those involved in cytokine production. HPs play key roles in such varied biological processes as metabolism, development and intracellular signalling. They differ considerably in their primary sequence and substrate specificity, but possess a catalytic core formed by an invariant quartet of active-site residues. Two histidine and two arginine residues cluster together within the HP active site and are thought to participate in a two-step dephosphorylation reaction. To date there has been little insight into any additional residues that might play an important functional role. In the present study, we identify and characterize an additional residue within the Sts phosphatases (Sts-1 Arg383 or Sts-2 Arg369) that is critical for catalytic activity and intracellular function. Mutation of Sts-1 Arg383 to an alanine residue compromises the enzyme's activity and renders Sts-1 unable to suppress TCR-induced cytokine induction. Of the multiple amino acids substituted for Arg383, only lysine partially rescues the catalytic activity of Sts-1. Although Sts-1 Arg383 is conserved in all Sts homologues, it is only conserved in one of the two sub-branches of HPs. The results of the present study highlight an essential role for Sts-1 phosphatase activity in regulating T-cell activation and add a new dimension of complexity to our understanding of HP catalytic activity.
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Trinh TB, Xiao Q, Pei D. Profiling the substrate specificity of protein kinases by on-bead screening of peptide libraries. Biochemistry 2013; 52:5645-55. [PMID: 23848432 DOI: 10.1021/bi4008947] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A robust, high-throughput method has been developed to screen one-bead-one-compound peptide libraries to systematically profile the sequence specificity of protein kinases. Its ability to provide individual sequences of the preferred substrates permits the identification of sequence contextual effects and nonpermissive residues. Application of the library method to kinases Pim1, MKK6, and Csk revealed that Pim1 and Csk are highly active toward peptide substrates and recognize specific sequence motifs, whereas MKK6 has little activity or sequence selectivity against peptide substrates. Pim1 recognizes peptide substrates of the consensus RXR(H/R)X(S/T); it accepts essentially any amino acid at the S/T-2 and S/T+1 positions, but strongly disfavors acidic residues (Asp or Glu) at the S/T-2 position and a proline residue at the S/T+1 position. The selected Csk substrates show strong sequence covariance and fall into two classes with the consensus sequences of (D/E)EPIYϕXϕ and (D/E)(E/D)S(E/D/I)YϕXϕ (where X is any amino acid and ϕ is a hydrophobic amino acid). Database searches and in vitro kinase assays identified phosphatase PTP-PEST as a Pim1 substrate and phosphatase SHP-1 as a potential Csk substrate. Our results demonstrate that the sequence specificity of protein kinases is defined not only by favorable interactions between permissive residue(s) on the substrate and their cognate binding site(s) on the kinase but also by repulsive interactions between the kinase and nonpermissive residue(s).
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Affiliation(s)
- Thi B Trinh
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
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Xiao Q, Luechapanichkul R, Zhai Y, Pei D. Specificity profiling of protein phosphatases toward phosphoseryl and phosphothreonyl peptides. J Am Chem Soc 2013; 135:9760-7. [PMID: 23758517 DOI: 10.1021/ja401692t] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A combinatorial library method was developed to systematically profile the substrate specificity of protein phosphatases toward phosphoseryl (pS) and phosphothreonyl (pT) peptides. Application of this method and a previously reported phosphotyrosyl (pY) library screening technique to dual-specificity phosphatase (DUSP) VH1 of vaccinia virus revealed that VH1 is highly active toward both pS/pT and pY peptides. VH1 exhibits different and more stringent sequence specificity toward pS/pT than pY substrates. Unlike previously characterized protein tyrosine phosphatases (PTPs), the activity and specificity of VH1 are primarily determined by the amino acid residues C-terminal to the pS, pT, or pY residue. In contrast, the mammalian VH1-related (VHR) DUSP has intrinsically low catalytic activity toward pS and pT substrates, suggesting that its primary physiological function is to dephosphorylate pY residues in substrate proteins. This method is applicable to other DUSPs and protein-serine/threonine phosphatases, and the substrate specificity data will be useful for identifying the physiological substrates of these enzymes.
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Affiliation(s)
- Qing Xiao
- Department of Chemistry and Biochemistry, The Ohio State University, 484 West 12th Ave., Columbus, Ohio 43210, USA
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Aitken RJ, Mehers KL, Williams AJ, Brown J, Bingley PJ, Holl RW, Rohrer TR, Schober E, Abdul-Rasoul MM, Shield JPH, Gillespie KM. Early-onset, coexisting autoimmunity and decreased HLA-mediated susceptibility are the characteristics of diabetes in Down syndrome. Diabetes Care 2013; 36:1181-5. [PMID: 23275362 PMCID: PMC3631858 DOI: 10.2337/dc12-1712] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Down syndrome (DS) is associated with an increased risk of diabetes, particularly in young children. HLA-mediated risk is however decreased in children with DS and diabetes (DSD). We hypothesized that early-onset diabetes in children with DS is etiologically different from autoimmune diabetes. RESEARCH DESIGN AND METHODS Clinical and immunogenetic markers of autoimmune diabetes were studied in 136 individuals with DSD and compared with 194 age- and sex-matched individuals with type 1 diabetes, 222 with DS, and 671 healthy controls. HLA class II was analyzed by sequence-specific primed PCR. Islet autoantibodies were measured by radioimmunoassay. RESULTS Age at onset of diabetes was biphasic, with 22% of DS children diagnosed before 2 years of age, compared with only 4% in this age-group with type 1 diabetes in the general population (P < 0.0001). The frequency of the highest-risk type 1 diabetes-associated HLA genotype, DR3-DQ2/DR4-DQ8, was decreased in both early- and later-onset DSD compared with age-matched children with type 1 diabetes (P < 0.0001), although HLA DR3-DQ2 genotypes were increased (P = 0.004). Antibodies to GAD were observed in all five samples tested from children diagnosed at ≤2 years of age, and persistent islet autoantibodies were detected in 72% of DSD cases. Thyroid and celiac disease were diagnosed in 74 and 14%, respectively, of the DSD cohort. CONCLUSIONS Early-onset diabetes in children with DS is unlikely to be etiologically different from autoimmune diabetes occurring in older DS children. Overall, these studies demonstrate more extreme autoimmunity in DSD typified by early-onset diabetes with multiple autoimmunity, persistent islet autoantibodies, and decreased HLA-mediated susceptibility.
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Hintersteiner M, Auer M. A two-channel detection method for autofluorescence correction and efficient on-bead screening of one-bead one-compound combinatorial libraries using the COPAS fluorescence activated bead sorting system. Methods Appl Fluoresc 2013; 1:017001. [PMID: 29148437 DOI: 10.1088/2050-6120/1/1/017001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
One-bead one-compound combinatorial library beads exhibit varying levels of autofluorescence after solid phase combinatorial synthesis. Very often this causes significant problems for automated on-bead screening using TentaGel beads and fluorescently labeled target proteins. Herein, we present a method to overcome this limitation when fluorescence activated bead sorting is used as the screening method. We have equipped the COPAS bead sorting instrument with a high-speed profiling unit and developed a spectral autofluorescence correction method. The correction method is based on a simple algebraic operation using the fluorescence data from two detection channels and is applied on-the-fly in order to reliably identify hit beads by COPAS bead sorting. Our method provides a practical tool for the fast and efficient isolation of hit beads from one-bead one-compound library screens using either fluorescently labeled target proteins or biotinylated target proteins. This method makes hit bead identification easier and more reliable. It reduces false positives and eliminates the need for time-consuming pre-sorting of library beads in order to remove autofluorescent beads.
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Atypical protein phosphatases: emerging players in cellular signaling. Int J Mol Sci 2013; 14:4596-612. [PMID: 23443160 PMCID: PMC3634448 DOI: 10.3390/ijms14034596] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 02/18/2013] [Accepted: 02/20/2013] [Indexed: 12/23/2022] Open
Abstract
It has generally been considered that protein phosphatases have more diverse catalytic domain structures and mechanisms than protein kinases; however, gene annotation efforts following the human genome project appeared to have completed the whole array of protein phosphatases. Ser/Thr phosphatases are divided into three subfamilies that have different structures from each other, whereas Tyr phosphatases and dual-specificity phosphatases targeting Tyr, Ser and Thr belong to a single large family based on their common structural features. Several years of research have revealed, however, the existence of unexpected proteins, designated here as “atypical protein phosphatases”, that have structural and enzymatic features different from those of the known protein phosphatases and are involved in important biological processes. In this review, we focus on the identification and functional characterization of atypical protein phosphatases, represented by eyes absent (EYA), suppressor of T-cell receptor signaling (Sts) and phosphoglycerate mutase family member 5 (PGAM5) and discuss their biological significance in cellular signaling.
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White AD, Keefe AJ, Nowinski AK, Shao Q, Caldwell K, Jiang S. Standardizing and simplifying analysis of peptide library data. J Chem Inf Model 2013; 53:493-9. [PMID: 23327110 DOI: 10.1021/ci300484q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide libraries allow researchers to quickly find hundreds of peptide sequences with a desired property. Currently, the large amount of data generated from peptide libraries is analyzed by hand, where researchers search for repeating patterns in the peptide sequences. Such patterns are called motifs. In this work, we describe a set of algorithms which allow quick, efficient, and standard analysis of peptide libraries. Four main techniques are described: (1) choice of the number of motifs present in a peptide library; (2) separation of the peptides into groups of similar sequences; (3) fitting of a model to the peptides to extract motifs; (4) analysis of the library using quantitative structure-property relationships if no clear motifs are present. The application of five previously published data sets shows these techniques can automatically repeat the work of experts quickly and allow much more flexibility in analysis. A new way of visually presenting peptide libraries is also described, which allows visual inspection of the grouping and spread of sequences. The algorithms have been implemented in an open-source plug-in called "peplib" and an online web application.
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Affiliation(s)
- Andrew D White
- Department of Chemical Engineering, University of Washington, Seattle, Washington, USA
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Luechapanichkul R, Chen X, Taha HA, Vyas S, Guan X, Freitas MA, Hadad CM, Pei D. Specificity profiling of dual specificity phosphatase vaccinia VH1-related (VHR) reveals two distinct substrate binding modes. J Biol Chem 2013; 288:6498-510. [PMID: 23322772 DOI: 10.1074/jbc.m112.449611] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vaccinia VH1-related (VHR) is a dual specificity phosphatase that consists of only a single catalytic domain. Although several protein substrates have been identified for VHR, the elements that control the in vivo substrate specificity of this enzyme remain unclear. In this work, the in vitro substrate specificity of VHR was systematically profiled by screening combinatorial peptide libraries. VHR exhibits more stringent substrate specificity than classical protein-tyrosine phosphatases and recognizes two distinct classes of Tyr(P) peptides. The class I substrates are similar to the Tyr(P) motifs derived from the VHR protein substrates, having sequences of (D/E/ϕ)(D/S/N/T/E)(P/I/M/S/A/V)pY(G/A/S/Q) or (D/E/ϕ)(T/S)(D/E)pY(G/A/S/Q) (where ϕ is a hydrophobic amino acid and pY is phosphotyrosine). The class II substrates have the consensus sequence of (V/A)P(I/L/M/V/F)X1-6pY (where X is any amino acid) with V/A preferably at the N terminus of the peptide. Site-directed mutagenesis and molecular modeling studies suggest that the class II peptides bind to VHR in an opposite orientation relative to the canonical binding mode of the class I substrates. In this alternative binding mode, the Tyr(P) side chain binds to the active site pocket, but the N terminus of the peptide interacts with the carboxylate side chain of Asp(164), which normally interacts with the Tyr(P) + 3 residue of a class I substrate. Proteins containing the class II motifs are efficient VHR substrates in vitro, suggesting that VHR may act on a novel class of yet unidentified Tyr(P) proteins in vivo.
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Affiliation(s)
- Rinrada Luechapanichkul
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
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Kunys AR, Lian W, Pei D. Specificity profiling of protein-binding domains using one-bead-one-compound Peptide libraries. CURRENT PROTOCOLS IN CHEMICAL BIOLOGY 2012; 4:331-55. [PMID: 23788558 PMCID: PMC3690186 DOI: 10.1002/9780470559277.ch120125] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
One-bead-one-compound (OBOC) libraries consist of structurally related compounds (e.g., peptides) covalently attached to a solid support, with each resin bead carrying a unique compound. OBOC libraries of high structural diversity can be rapidly synthesized and screened without the need for any special equipment, and therefore can be employed in any chemical or biochemical laboratory. OBOC peptide libraries have been widely used to map the ligand specificity of proteins, to determine the substrate specificity of enzymes, and to develop inhibitors against macromolecular targets. They have proven particularly useful in profiling the binding specificity of protein modular domains (e.g., SH2 domains, BIR domains, and PDZ domains); subsequently, the specificity information can be used to predict the protein targets of these domains. The protocols outlined in this article describe the methodologies for synthesizing and screening OBOC peptide libraries against SH2 and PDZ domains, and the related data analysis. Curr. Protoc. Chem. Biol. 4:331-355 © 2012 by John Wiley & Sons, Inc.
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Affiliation(s)
- Andrew R. Kunys
- Department of Chemistry and Biochemistry, The Ohio State University
| | - Wenlong Lian
- Department of Chemistry and Biochemistry, The Ohio State University
| | - Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University
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TULA-2, a novel histidine phosphatase, regulates bone remodeling by modulating osteoclast function. Cell Mol Life Sci 2012; 70:1269-84. [PMID: 23149425 DOI: 10.1007/s00018-012-1203-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 10/16/2012] [Accepted: 10/18/2012] [Indexed: 10/27/2022]
Abstract
Bone is a dynamic tissue that depends on the intricate relationship between protein tyrosine kinases (PTK) and protein tyrosine phosphatases (PTP) for maintaining homeostasis. PTKs and PTPs act like molecular on and off switches and help modulate differentiation and the attachment of osteoclasts to bone matrix regulating bone resorption. The protein T cell ubiquitin ligand-2 (TULA-2), which is abundantly expressed in osteoclasts, is a novel histidine phosphatase. Our results show that of the two family members, only TULA-2 is expressed in osteoclasts and that its expression is sustained throughout the course of osteoclast differentiation, suggesting that TULA-2 may play a role during early as well late stages of osteoclast differentiation. Skeletal analysis of mice that do not express TULA or TULA-2 proteins (DKO mice) revealed that there was a decrease in bone volume due to increased osteoclast numbers and function. Furthermore, in vitro experiments indicated that bone marrow precursor cells from DKO mice have an increased potential to form osteoclasts. At the molecular level, the absence of TULA-2 in osteoclasts results in increased Syk phosphorylation at the Y352 and Y525/526 residues and activation of phospholipase C gamma 2 (PLCγ2) upon engagement of immune-receptor-tyrosine-based-activation-motif (ITAM)-mediated signaling. Furthermore, expression of a phosphatase-dead TULA-2 leads to increased osteoclast function. Taken together, these results suggest that TULA-2 negatively regulates osteoclast differentiation and function.
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Hintersteiner M, Buehler C, Auer M. On-Bead Screens Sample Narrower Affinity Ranges of Protein-Ligand Interactions Compared to Equivalent Solution Assays. Chemphyschem 2012; 13:3472-80. [DOI: 10.1002/cphc.201200117] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 06/27/2012] [Indexed: 11/06/2022]
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Hong J, Hu K, Yuan Y, Sang Y, Bu Q, Chen G, Yang L, Li B, Huang P, Chen D, Liang Y, Zhang R, Pan J, Zeng YX, Kang T. CHK1 targets spleen tyrosine kinase (L) for proteolysis in hepatocellular carcinoma. J Clin Invest 2012; 122:2165-75. [PMID: 22585575 DOI: 10.1172/jci61380] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 04/04/2012] [Indexed: 12/14/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies resistant to current chemotherapies or radiotherapies, which makes it urgent to identify new therapeutic targets for HCC. In this study, we found that checkpoint kinase 1 (CHK1) was frequently overexpressed and correlated with poor clinical outcome in patients with HCC. We further showed that the CHK1 inhibitor GÖ6976 was capable of sensitizing HCC cells to cisplatin, indicating that CHK1 may have oncogenic function in HCC. We found that CHK1 phosphorylated the tumor suppressor spleen tyrosine kinase (L) (SYK[L]) and identified the phosphorylation site at Ser295. Furthermore, CHK1 phosphorylation of SYK(L) promoted its subsequent proteasomal degradation. Expression of a nonphosphorylated mutant of SYK(L) was more efficient at suppressing proliferation, colony formation, mobility, and tumor growth in HCC lines. Importantly, a strong inverse correlation between the expression levels of CHK1 and SYK(L) was observed in patients with HCC. Collectively, our data demonstrate that SYK(L) is a substrate of CHK1 in tumor cells and suggest that targeting the CHK1/SYK(L) pathway may be a promising strategy for treating HCC.
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Affiliation(s)
- Jian Hong
- State Key Laboratory of Oncology in South China
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de Castro RO, Zhang J, Groves JR, Barbu EA, Siraganian RP. Once phosphorylated, tyrosines in carboxyl terminus of protein-tyrosine kinase Syk interact with signaling proteins, including TULA-2, a negative regulator of mast cell degranulation. J Biol Chem 2012; 287:8194-204. [PMID: 22267732 DOI: 10.1074/jbc.m111.326850] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the high affinity IgE-binding receptor (FcεRI) results in the tyrosine phosphorylation of two conserved tyrosines located close to the COOH terminus of the protein-tyrosine kinase Syk. Synthetic peptides representing the last 10 amino acids of the tail of Syk with these two tyrosines either nonphosphorylated or phosphorylated were used to precipitate proteins from mast cell lysates. Proteins specifically precipitated by the phosphorylated peptide were identified by mass spectrometry. These included the adaptor proteins SLP-76, Nck-1, Grb2, and Grb2-related adaptor downstream of Shc (GADS) and the protein phosphatases SHIP-1 and TULA-2 (also known as UBASH3B or STS-1). The presence of these in the precipitates was further confirmed by immunoblotting. Using the peptides as probes in far Western blots showed direct binding of the phosphorylated peptide to Nck-1 and SHIP-1. Immunoprecipitations suggested that there were complexes of these proteins associated with Syk especially after receptor activation; in these complexes are Nck, SHIP-1, SLP-76, Grb2, and TULA-2 (UBASH3B or STS-1). The decreased expression of TULA-2 by treatment of mast cells with siRNA increased the FcεRI-induced tyrosine phosphorylation of the activation loop tyrosines of Syk and the phosphorylation of phospholipase C-γ2. There was parallel enhancement of the receptor-induced degranulation and activation of nuclear factor for T cells or nuclear factor κB, indicating that TULA-2, like SHIP-1, functions as a negative regulator of FcεRI signaling in mast cells. Therefore, once phosphorylated, the terminal tyrosines of Syk bind complexes of proteins that are positive and negative regulators of signaling in mast cells.
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Affiliation(s)
- Rodrigo Orlandini de Castro
- Receptors and Signal Transduction Section, Oral Infection and Immunity Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA
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Nonsegmental vitiligo and autoimmune mechanism. Dermatol Res Pract 2011; 2011:518090. [PMID: 21804820 PMCID: PMC3144695 DOI: 10.1155/2011/518090] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Revised: 05/30/2011] [Accepted: 06/01/2011] [Indexed: 11/18/2022] Open
Abstract
Nonsegmental vitiligo is a depigmented skin disorder showing acquired, progressive, and depigmented lesions of the skin, mucosa, and hair. It is believed to be caused mainly by the autoimmune loss of melanocytes from the involved areas. It is frequently associated with other autoimmune diseases, particularly autoimmune thyroid diseases including Hashimoto's thyroiditis and Graves' disease, rheumatoid arthritis, type 1 diabetes, psoriasis, pernicious anemia, systemic lupus erythematosus, Addison's disease, and alopecia areata. This indicates the presence of genetically determined susceptibility to not only vitiligo but also to other autoimmune disorders. Here, we summarize current understanding of autoimmune pathogenesis in non-segmental vitiligo.
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Regulation and function of syk tyrosine kinase in mast cell signaling and beyond. JOURNAL OF SIGNAL TRANSDUCTION 2011; 2011:507291. [PMID: 21776385 PMCID: PMC3135164 DOI: 10.1155/2011/507291] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 02/23/2011] [Indexed: 01/16/2023]
Abstract
The protein tyrosine kinase Syk plays a critical role in FcεRI signaling in mast cells. Binding of Syk to phosphorylated immunoreceptor tyrosine-based activation motifs (p-ITAM) of the receptor subunits results in conformational changes and tyrosine phosphorylation at multiple sites that leads to activation of Syk. The phosphorylated tyrosines throughout the molecule play an important role in the regulation of Syk-mediated signaling. Reconstitution of receptor-mediated signaling in Syk−/− cells by wild-type Syk or mutants which have substitution of these tyrosines with phenylalanine together with in vitro assays has been useful strategies to understand the regulation and function of Syk.
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San Luis B, Sondgeroth B, Nassar N, Carpino N. Sts-2 is a phosphatase that negatively regulates zeta-associated protein (ZAP)-70 and T cell receptor signaling pathways. J Biol Chem 2011; 286:15943-54. [PMID: 21393235 PMCID: PMC3091203 DOI: 10.1074/jbc.m110.177634] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Revised: 03/06/2011] [Indexed: 11/06/2022] Open
Abstract
T cell activity is controlled in large part by the T cell receptor (TCR). The TCR detects the presence of foreign pathogens and activates the T cell-mediated immune reaction. Numerous intracellular signaling pathways downstream of the TCR are involved in the process of T cell activation. Negative regulation of these pathways helps prevent excessive and deleterious T cell responses. Two homologous proteins, Sts-1 and Sts-2, have been shown to function as critical negative regulators of TCR signaling. The phosphoglycerate mutase-like domain of Sts-1 (Sts-1(PGM)) has a potent phosphatase activity that contributes to the suppression of TCR signaling. The function of Sts-2(PGM) as a phosphatase has been less clear, principally because its intrinsic enzyme activity has been difficult to detect. Here, we demonstrate that Sts-2 regulates the level of tyrosine phosphorylation on targets within T cells, among them the critical T cell tyrosine kinase Zap-70. Utilizing new phosphorylated substrates, we demonstrate that Sts-2(PGM) has clear, albeit weak, phosphatase activity. We further pinpoint Sts-2 residues Glu-481, Ser-552, and Ser-582 as specificity determinants, in that an Sts-2(PGM) triple mutant in which these three amino acids are altered to their counterparts in Sts-1(PGM) has substantially increased activity. Our results suggest that the phosphatase activities of both suppressor of TCR signaling homologues cooperate in a similar but independent fashion to help set the threshold for TCR-induced T cell activation.
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Affiliation(s)
- Boris San Luis
- From the Departments of Molecular Genetics and Microbiology and
| | - Ben Sondgeroth
- Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794
| | - Nicolas Nassar
- Physiology and Biophysics, Stony Brook University, Stony Brook, New York 11794
| | - Nick Carpino
- From the Departments of Molecular Genetics and Microbiology and
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Ren L, Chen X, Luechapanichkul R, Selner NG, Meyer TM, Wavreille AS, Chan R, Iorio C, Zhou X, Neel BG, Pei D. Substrate specificity of protein tyrosine phosphatases 1B, RPTPα, SHP-1, and SHP-2. Biochemistry 2011; 50:2339-56. [PMID: 21291263 DOI: 10.1021/bi1014453] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We determined the substrate specificities of the protein tyrosine phosphatases (PTPs) PTP1B, RPTPα, SHP-1, and SHP-2 by on-bead screening of combinatorial peptide libraries and solution-phase kinetic analysis of individually synthesized phosphotyrosyl (pY) peptides. These PTPs exhibit different levels of sequence specificity and catalytic efficiency. The catalytic domain of RPTPα has very weak sequence specificity and is approximately 2 orders of magnitude less active than the other three PTPs. The PTP1B catalytic domain has modest preference for acidic residues on both sides of pY, is highly active toward multiply phosphorylated peptides, but disfavors basic residues at any position, a Gly at the pY-1 position, or a Pro at the pY+1 position. By contrast, SHP-1 and SHP-2 share similar but much narrower substrate specificities, with a strong preference for acidic and aromatic hydrophobic amino acids on both sides of the pY residue. An efficient SHP-1/2 substrate generally contains two or more acidic residues on the N-terminal side and one or more acidic residues on the C-terminal side of pY but no basic residues. Subtle differences exist between SHP-1 and SHP-2 in that SHP-1 has a stronger preference for acidic residues at the pY-1 and pY+1 positions and the two SHPs prefer acidic residues at different positions N-terminal to pY. A survey of the known protein substrates of PTP1B, SHP-1, and SHP-2 shows an excellent agreement between the in vivo dephosphorylation pattern and the in vitro specificity profiles derived from library screening. These results suggest that different PTPs have distinct sequence specificity profiles and the intrinsic activity/specificity of the PTP domain is an important determinant of the enzyme's in vivo substrate specificity.
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Affiliation(s)
- Lige Ren
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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Takeda K. PGAM5: A Novel Type of Protein Serine/Threonine Phosphatase That Exists in the Mitochondria. J Oral Biosci 2011. [DOI: 10.2330/joralbiosci.53.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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48
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Taked K. PGAM5: A Novel Type of Protein Serine/Threonine Phosphatase That Exists in the Mitochondria. J Oral Biosci 2011. [DOI: 10.1016/s1349-0079(11)80014-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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